Hydraulic speed control apparatus



W. R. TUCKER HYDRAULIC SPEED CONTROL APPARATUS March 2, 1948.

Filed Feb. 23, 1944 lfgi.

INV ENTOR WARREN R. TUCKER,

ATTORN EYS Patented Mar. 2, 1948 UNITED STATES PATENT OFFICE,

HYDRAULIC SPEED CONTROL APPARATUS Warren R. Tucker, Dayton, Ohio, assignor to 1 H-P-M Development Corporation, Wilmington,

Del., a corporation of Delaware Application February 23, 1944, Serial No. 523,505

This invention relates to control systems and, in particular, to hydraulic control systems. This invention has to do, in particular, with the simultaneous control of two or more moving elements such as rotary or translating members.

There are many classes of workin which it Is desired to more or less accurately synchronize the operation of individual elements. on machines for winding continuous materials such as thread or paper it is necessary to have a number of rollers all of which rotate at the same speed. Thus, a constant tension is exerted on the material being wound and a properly uniform product results. It will be obvious that any great difierence in speed between a pair of rollers carrying the same thread will result in the breakage of the strand.

Other examples of arts requiring coordination between the various machine elements include paper making machines, glass making machines and various other types of rolling or winding operations.

One method of driving these various elements, and at the same time attempting to synchronize the same, has been to provide separate hydraulic motor drives for each element and to direct the exhaust fluid from one motor to the inlet of the next. This method of synchronizing several dif-- ferent elements has proved to be unsatisfactory since each of the driving motors must be identical with every other as regard displacement and leakage of pressure fluid therethrough. Furthermore, in a series arrangement such as this, the errors outlined above are" cumulative and the discrepancy between the actual position of the driven element and the desired position becomes greater as the operation continues.

Accordingly, it is the primary object of the present invention to provide a control system for a plurality of driven elements whereby the same may be substantially synchronized.

It is a further object to provide an improved hydraulic control system for accomplishing the above.

It is another object of this invention to provide a hydraulic control system for synchronizing the operation of several different driven elements, while providing individual controls for adjusting the speed of each element independently of the others.

These and other objects will be apparent upon reference to the following detailed description and attached drawing, in which:

Figure 1 is a view of a hydraulic circuit which, for the most. part, is presented diagrammatical- 9 Claims. (01. 60-91) For example, ing apart of this system.

2 1y for the-purpose of better illustrating this invention, and

Figure 2 is a perspective view of the throttle valve member by which the simultaneous control of a plurality of motors is obtained; and

Figure 3 is a cross-section taken on the line,

form- 3-3 of Figure 1, showing the throttling unit General arrangement The general arrangement of this invention, as shown in Figure 1, comprises a plurality of hydraulic motors and a plurality of pumps for supplying actuating fluid thereto. The plurality of motors provide the driving power for an equal number of machine elements, such as rollers, the

sible to invert this arrangement and provide variable displacement motors and constant displacement pumps.

Detailed description Referring to Figure 1, there is provided a plurality of driven members such as hydraulic motors indicated at 5, 6 and 1. These motors are of the constant displacement type, but as will be explained later, may be replaced by variable displacement motors.

Pressure fiuid is supplied to the motors 5, 6 and I by means of conduits 8, 9 and I0 respectively, which in turn are connected to the outlets of the pumps II, I2 and I3, respectively. The pumps II, I2 and I3 draw fluid from a reservoir II through the conduits I5, I6 and II, respectively. The pumps II, I2 and I3 are preferably of the variable displacement type but may, as will bevcome hereinafter apparent, be replaced by constant delivery or constant displacement pumps 3 The control unit 2| is freely exhausted by means of a conduit 22 to the reservoir or any other suitable fluid collecting means. The control unit 2i comprises a casing 28 having anaxial bore 24 therein. The conduits l8, l8 and 20 communicate with the bore 24 and the bore 24, in turn, is exhausted by means of the conduit 22..

Inserted within the bore 24 is a member 25 which is provided with notches 28 which are adapted to be positioned between the inlet and outlet conduits of the control unit 2|. The member 25 terminates, at the one end, in a square shank or other suitable means for adjusting the angular position thereof as indicated at 21. The

portion 2'! extends externally of the casing 23,

to the left as shown in Figure 1, and a suitable.

locking means such as the knurled hand wheel 28 provides a means for locking the member 25 in any particular position of adjustment.

As will be seen from Figure 3, the notches 26 in the member 25 provide a means for creating a restriction between the inlet conduit and the exhaust conduit. This restriction may be varied by adjusting the angular position of the member 25. It will be apparent that the restriction offered to the flow of fluid from each of the conduits l8, l9 and 20 is varied simultaneously and identically as the member 25 is adjusted.

Referring now to the variable displacement pump units, and particularly to the pump II, this will be seen to comprise a shiftable flow controlling member 28 having an adjustable yielding means such as the spring 29 continuously urging the same toward full delivery position. The spring 28 is adjusted by means of the threaded rod 30 and the hand wheel 4,

Opposing the thrust of the spring 29 is a 4 plunger 32 to which is attached a piston 33, the

latter being reciprocable within a cylinder 34. The establishment of a predetermined pressure within the right hand end of cylinder 34 is efiective to cause the piston 33 through the plunger 32 to move the flow controlling member 28 to the left against the thrust of the spring 29 thereby to reduce the delivery of the pump associated therewith.

The pressure for actuating the piston 33 is supplied to the cylinder 34 by means of a conduit 35 which is connected with the exhaust conduit l8.

Operation In operation, the pumps ll, l2 and I8 are driven in any suitable manner from a single power source or from individual power sources. The pumps deliver through the conduits 8, 9 and ill to the motors 5, 6 and I, respectively, the motors being provided with output shafts 36, 31 and 38, respectively for driving rolls or other suitable machine elements.

The exhausts from the motors are conducted to the control unit 25 where each is throttled an identical amount in passing thenethrough to the exhaust conduit 22.

The restrictions within the control unit 2i, created by the notches 28, is effective to maintain a predetermined pressure in each of the conduits l8, l8 and 20, which pressures are conducted through the conduits 85 to the control cylinders 34 to act upon the pistons 33.

The effect of the pressure conducted to each cylinder 3| through the conduit 35 associated therewith is to move the shiftable flow control member of the associated pump toward'neutral against the thrust of the spring 29. The pump will move toward neutral, reducing its delivery and, therefore, the exhaust from the motor, until the pressure created at the motor exhaust by the control unit is reduced to such a point that the thrusts of the spring and the piston 33 are exactly balanced. This action takes place in each of the three pump-motor units and the three motors will, when the thrusts of the three springs 22 are properly adjusted, be running with equal speeds, I

The effect of the restrictions in the motor exhaust conduits is to maintain this speed constant, inasmuch as a reduction thereocf'will permit the spring 28 to increase the delivery of the pump, and an increase thereof will cause the piston 23 to move to reduce the delivery of the pump.

In case it is desired to operate one or more of the motors at a different speed from the others, this may be accomplished by adjusting the spring 28 by means 01' the threaded rod 30 and hand wheel 3|. As the thrust of the spring is increased the motor associated with that pump will operate at a greater speed than the others and vice-versa as the thrust of the spring is decreased. The manual adjusting means for adjusting the thrust of the spring of each pump is likewise useful for making minor adjustments such as might occur on account of leakage of hydraulic fluid or from slight dissimiiaritdes in the displacements of the various pumps and motors.

It will be apparent that, once the speed ratios of the various motors relative to one another have been adjusted by means of the springs 29, the adjustment of the central control means 2| will be effective to cause proportional changes in the speeds of all the motors simultaneously and without changing the aforementioned speed ratios.

It will also be apparent that this invention is not limited to the control of three motors, as shown, but may be extended to control as many motors as it is desired. It will also be apparent that either the motor or the pump or both could be variable displacement units without in any way departing from the spirit of this invention.

Accordingly, it will be understood that I do not wish to be limited by the specific structures and arrangements shown in the drawings, but desire to comprehend such modifications as come within the scope of the appended claims.

Having thus fully described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In a hydraulic system; a plurality of fixed displacement fluid operable motors having fluid inlets and fluid outlets: a movable work member associated with each of said motors to be driven thereby; a plurality of variable delivery pumps respectively hydraulically connected with said motor inlets and having movable flow control members; a plurality of choke valves having their inlets respectively hydraulically connected with said motor outlets, the outlets of said chokes being connected to exhaust; -a member common to all of said choke valves and movable to adjust the throttling effects thereof simultaneously and equally: a plurality of fluid operable plungers respectively hydraulically connected to the inv lets of said chokes. said plungers also being respectively connected with the flow control members of said variable delivery pumps: a plurality;

of yielding means continuously urging said flow control members toward increased delivery position; and means for adjusting the thrust of each 01' said yielding means whereby the pressures created at the inlets of said choices by the 'flow tlons in pressure at the inlets of said chokes to vary the displacements of said pumps relative to said motors and inversely to said pressure variations, thereby to maintain the speeds of said oi fluid through said motors will urge said flow -motor inlets and having movable flow-control members; .a plurality oi. choke valves having their inlets respectively hydraulically connected with said motor outlets, the outlets or said chokes being connected to exhaust; a member common to all of said choke valves and movable to adiust the throttling eflects thereof simultaneously and equally; a plurality oi fluid operable plungers respectively hydraulically connected to the inlets oi said chokes, said plungers also'being respectively connected with the flow control members of said variable delivery pumps; a plurality of motors and, therefore, the speed oi said work members substantially constant.

' 5. In a hydraulic system; a plurality of fluid operable motors having fluid inlets and fluid outlets; a work shaft associated with each of said motors to be driven thereby; a plurality of variable delivery pumps respectively hydraulically connected with said motor inlets; a plurality of throttle valves having their inlets respectively hydraulically connected with said motor outlets; means for adjusting the throttling effects of all of said throttle valves simultaneously; a plurality of fluid operable servomotors respectively hydraulically connected to the inlets of said throttle valves and associated with said variable delivery pumps and adapted, in response to variations in pressure at the inlets of said throttle valves, to actuate said servoinotors to vary the trol members toward increased delivery position;

whereby the pressures created at the inlets 01' said chokes by the flow of fluid through said motors will urge said flow control members toward reduced delivery position with a thrust equal to that of said yielding means, the thrust of the latter being in accordance with the individual adjustment thereof.

3. In a hydraulic system: a plurality of fluid operable motors having fluid inlets and fluid outlets; amovable work member associated with each of said motors to be driven thereby; a plurality oi pumps respectively hydraulically connected with said motor inlets; a plurality of throttle valves having their inlets respectively hydraulically connected with said motor outlets and their outlets connected to exhaust; a means associated with all 01 said throttle valves and selectively operable to adjust the throttling eiiects thereof simultaneously and equally; a plurality oi fluid operable means respectively hydraulically connected to the inlets of said throttle valves and operable, in response to variations in pressure at the inlets oi said chokes, to vary the relative displacements of said pumps and said motors, thereby to maintain the speeds of said motors and, therefore, the speed of said work members substantially constant.

4. In a hydraulic system; a plurality or fluid operable motors having fluid inlets and fluid outlets; a movable work member associated with each or said motors to be driven thereby; a plurality of pumps respectively hydr ulically connected with said motor inlets; a plurality of throttle valves having their inlets respectively hydraulically connected with said motor outlets and their outlets connected to exhaust; a means associated with all or said throttle valves and selectively operable to adjust the throttling eiiects thereof simultaneously and equally; a plu-' rality or fluid operable means respectively hydraulically connected to the inlets of said throttle valves and operable, in response to variarates oi? delivery of said pumps thereby to maintain the speeds of said motors substantially constant. v

6. In a hydraulic system; a plurality of fluid operable motors having fluid inlets and fluid outlets; a work shaft associated with each or said motors to be driven thereby; a plurality of variable delivery pumps respectively hydraulically connected with said motor inlets; a plurality of throttle valves having their inlets respectively hydraulically connected with said motor outlets; means for adjusting the throttling effects of all of said throttle valves simultaneously; a plurality of fluid operable servomotors respectively hydralically connected to the inlets of said throttle valves and associated with said variable delivery pumps and adapted, in response to variations in pressure at the inlets of said throttle valves, to actuate said servomotors to vary the rates of delivery or said pumps inversely to said pressure variations, thereby to maintain the speeds of said motors substantially constant.

'7. In a system for selecting and controlling the speeds of a plurality of fluid operable motors having fluid inlets and fluid outlets; a fluid operable control means associated with each of said motors and operable, in response to a predetermined fluid pressure, to vary the supply oi'actuating fluid to said motor; a 'flow responsive means associated with the outlet oi said motor and operable to maintain a predetermined pressure at said motor outlet; conduit means hydraulically connecting said motor outlet with said fluid operable control means; means for adjusting each or said fluid operable control means independently ot the others; and means selectively operable ior adjusting all of said flow responsive means simultaneously and equally.

8. In ahydraulic system; a plurality of fluid.

operable motors; a source 0! pressure fluid for supplying actuating fluid to said motors; a. plurality of flow responsive means respectively asinverse proportion to the pressure applied tov said flow control means; and means for varying the response or each of said flow controllin means independently, whereby adjustment of said last mentioned means is effective to adjust the speed of the associated motor independently of the others and adjustment of said flow responsive means is effective to adjust the speeds of all of said motors simultaneously and in proportion.

9. Ina system for selecting and controlling the speeds or a plurality of fluid operable motors; a fluid pressure responsive control means associated with each of said motors; a flow responsive means serially connected with each of said motors and operable to create a pressure difference between its inlet and its outlet in proportion to the rate of fluid flow therethrough; means conveying the pressure difference generated by each of said flow responsive means to the control means associated with the same motor; means for adjusting each of said control means inde-- pendently of the others and means selectively 8 operable for adjusting all of said flow resp nsive means simultaneously and equally.

o WARREN R. TUCKER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,466,642 Crook Aug. 28, 1923 1,694,704 Dunbar Dec, 11, 1928 1,939,113 Ferris Dec. 12, 1933 2,105,824 Simonds Jan. 18, 1938 2,320,727 Herman et al June 1, 1943 FOREIGN PATENTS Number Country Date 201,235 Great Britain July 26, 1923 232,349 Great Britain Apr. 23, 1925 121,879 Switzerland Aug. 1, 1927 

